The answer is D.
Hope this helps!
Answer:
i would say D mostly because I don't know what the other ones mean
Explanation:
(just looked them up and I still think its D)
On the basis of the information above, a buffer with a pH = 9 can best be made by using
A pure NaH2PO4
B H3PO4 + H2PO4–
C H2PO4– + PO42–
D H2PO4– + HPO42–
E HPO42– + PO43
Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for [tex]\mathbf{H_3PO_4 , H_2PO^{-}_4 , HPO_4^{2-}}[/tex] are [tex]\mathbf{7\times 10^{-3}, \ \ 8\times 10^{-8} ,\ \ 5\times 10^{-13}}[/tex] respectively.
[tex]\mathbf{pka (H_3PO_4) = -log (7\times 10^{-3} )=2.2}[/tex]
[tex]\mathbf{pka (H_2PO_4^-) = -log (8\times 10^{-8} )=7.1}[/tex]
[tex]\mathbf{pka (HPO_4^{2-}) = -log (5\times 10^{-13} )=12.3}[/tex]
The reason while option D is the best answer is that, the value of pKa for both
[tex]\mathbf{H_2PO^{-}_4 ,\ \& \ HPO_4^{2-}}[/tex] lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
[tex]\mathbf{pH = pKa + log \Big( \dfrac{HPO_4^{2-}}{H_2PO_4^-} \Big)}[/tex]
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex]. Thus, option D is correct.
The buffers are the solutions of acids and base of appropriate pH, that are able to limit the change in pH in the reaction mixture.
Which compound is used for pH 9 buffer?The buffer pH is adjusted with the compounds that has been able to add base or acid to the solution.
For the formulation of buffer of specific pH, the acid and base solutions are required.
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex], as they are able to provide acid and base to the solution.
Thus, option D is correct.
Learn more about buffers, here:
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Calculate the volume in mL of 0.100 of CaCl2 needed to produce 1.00 g of CaCO3. there is an excess of Na2CO3
Answer:
100. mL
Explanation:
The computation of the volume in mL is shown below:
The balance equation of the double displacement reaction is
[tex]CaCl_{2} + Na_{2}CO_{3} \rightarrow 2 NaCl + CaCO_{3}[/tex]
Now determine the moles that corresponding to 1.00 g of CaCO₃
As,
The molar mass of CaCO₃ is 100.09 g/mol.
So,
= 1.00 g × 1 mol/100.09 g
= 0.0100 mol
Now
the moles of CaCl₂ needed to generate 0.0100 moles of CaCO₃
As we know that
The molar ratio of CaCl₂ to CaCO₃ is 1:1.
So, The moles of CaCl₂ needed is
= 1 ÷ 1 × 0.0100 mol
= 0.0100 mol.
Now volume of 0.100 M CaCl₂ that contains 0.0100 mol is
= 0.0100 mol × 1 L/0.100 mol × 1000 mL/1 L
= 100. mL
Steam is collected and observed to condense into liquid water. Which of the following would you expect to observe if a thermometer recorded the temperature of the substance?
SELECT AN ANSWER
The temperature would decrease.
The temperature would remain the same.
It would depend on the amount of steam.
The temperature would increase.
the water will be increased
Name the compound AgF
Answer: Silver (I) fluoride molecule · AgF
Classification: Inorganic compound (Could be salt)
Ionic compound (Silver is a metal)
Valence of F (F must form an octet): 7
Valence of Ag: 11
Total valence electrons: 18
Molar mass: 126.87 g/mol
Explanation:
I need help explaining what are the differences between Solids, Liquids, and Gases.
Explanation: solids are frozen like if you freeze tea it becomes a solid , liquids is like tea and gases is like when you boil water and it becomes a gas
Which of the following are true about an atom? Choose all that apply.
Answer:
Explanation:
Atoms are the building blocks of matter.
They are the smallest particles of an element that still have the element's properties.
All atoms are very small, but atoms of different elements vary in size.
Three main types of particles that make up all atoms are protons, neutrons, and electrons.
According to the graph, what is the instantaneous speed of the object at 5 seconds? *
Captionless Image
4 m/s
7 m/s
0.25 m/s
3 m/s
Answer:4m/s
Explanation:The reason why that the answer is because I am Smart.
does warm air or cool air hold more humidity.
Answer:
warm
Explanation:
A tank contains 10 liters of pure water. A solution of an unknown, but constant concentration of salt is flowing in at 0.5 liters per minute. The water is mixed well and drained at 1 liter per minute. After 20 minutes there are 10 grams of salt in the tank. (i) Give an adequate mathematical model for this scenario. Explain what each of your variables means. (ii) What is the concentration of the incoming salt solution
Answer:
i) ∴∫[tex]\frac{dA}{A}[/tex] = ∫ [tex]\frac{-1}{10} dt[/tex] ------ ( 1 )
ii) C = 4.303
Explanation:
Given data:
water in tank = 10 liters
concentration of salt flowing in = 0.5 liters/min
10 grams of salt is left in tank after 20 minutes
mixed water is drained at 1 liter per minute
i) Adequate mathematical model for the scenario
lets assume ; A( t ) amount of salt after t minute
A( t ) = 10grams where t = 20 minutes
differentiate A(t)
dA / dt = ( rate in ) - ( rate out )
= 0.5 * 0 - A/10
∴∫[tex]\frac{dA}{A}[/tex] = ∫ [tex]\frac{-1}{10} dt[/tex] ------ ( 1 )
ii) hence; In A = [tex]\frac{-1}{10} t + C[/tex] ----- ( 2 )
at t = 20 , A = 10grams
find C = In 10 + 2
= 2.303 + 2 = 4.303
back to ( 2 )
In A = [tex]\frac{-t}{10} + 4.303[/tex]
∴ A = e [tex]\frac{-t}{10} + 4.303[/tex]
You and your family are on vacation in the mountains. You are trying to locate the campsite where you will be staying but you cannot get a signal. What is one reason why your GPS is not responding.
Answer:
A satellite may be malfunctioning.
Line of sight may be blocked.
low batteries in your GPS.
help! help! plz give 4 different between orbit and orbital
Answer:
Differences between Orbit and Orbitals
Orbit
An orbit is the simple planar representation of an electron.
It can be simply defined as the path that gets established in a circular motion by revolving the electron around the nucleus
The shape of molecules cannot be explained by an orbit as they are non-directional by nature.
An orbit that is well-defined goes against the Heisenberg principle.
Orbital
An orbital refers to the dimensional motion of an electron around the nucleus in a three-dimensional motion.
An orbital can simply be defined as the space or the region where the electron is likely to be found the most.
The shapes of the molecules can be found out as they are directional by nature.
An ideal orbital agrees with the theory of Heisenberg’s Principles.
Find the mass of 2.40 moles of CO. gas..
Determine the empirical and molecular formulas of the mandelic acid
Answer:
Both empirical and molecular are C₈H₈O₃.
Explanation:
Hello!
In this case, according the attached picture, it is possible to figure out the molecular formula of the mandelic acid by counting each carbon, hydrogen and oxygen in the molecule.
In such a way, we can see the presence of eight carbon atoms, eight hydrogen atoms and three carbon atoms; thus, the molecular formula is:
C₈H₈O₃
Furthermore, since the empirical formula is the smallest representation of the molecular formula when we are able to simplify it, we evidence no simplification is possible, consequently, the empirical formula equals the molecular one.
Best regards!
Look at sample problem 19.10 in the 8th ed Silberberg book. Write the Ksp expression. Find the concentrations of the ions you need (in this case Ca2 and F-). Put those concentrations into the Ksp expression to calculate Q. Compare Q to K A common laboratory method for preparing a precipitate is to mix solutions containing the component ions. Does a precipitate form when 10. ml of 0.0010 M Ca(NO3)2 is mixed with 10. ml of 0.00010 M NaF
Answer:
Explanation:
From the information given:
[tex]CaF_2 \to Ca^{2+} + 2F^-[/tex]
[tex]Ksp = 3.2 \times 10^{-11}[/tex]
no of moles of [tex]Ca^{2+}[/tex] = 0.01 L × 0.0010 mol/L
no of moles of [tex]Ca^{2+}[/tex] = [tex]1 \times 10^{-5} \ mol[/tex]
no of moles of [tex]F^-[/tex] = 0.01 L × 0.00010 mol/L
no of moles of [tex]F^-[/tex] = [tex]1 \times 10^{-6}\ mol[/tex]
Total volume = 0.02 L
[tex][Ca^{2+}}] = \dfrac{1\times10^{-5} \ mol}{0.02 \ L} \\ \\ \\ \[[Ca^{2+}}] = 0.0005 \ mol/L[/tex]
[tex][F^{-}] = \dfrac{(1\times 10^{-6} \ mol)}{0.02 \ L}[/tex]
[tex][F^{-}] = 5 \times 10^{-5} \ mol/L[/tex]
[tex]Q = [Ca^{2+}][F^-]^2 \\ \\ Q = 0.0005 \times (5\times 10^{-5})^2 \\ \\ Q = 1.25 \times 10^{-12}[/tex]
Since Q<ksp, then there will no be any precipitation of CaF2
What happens to algae when the temperature in the ocean becomes too hot?
O The algae are susceptible to infection.
O The algae become pale.
O The algae photosynthesize faster.
O The algae lose their ability to photosynthesize
Answer:
The algae lose their ability to photosynthesize.
Explanation:
Because the algae turn the energy from the sunlight into chemicals.
Hoped this helped!
50 POINTS
Which of the following correctly describes a compound?
A. The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
B. The atoms have no set ratio for how the atoms can combine, and they are not chemically bonded together.
C. The atoms can only combine in fixed ratios, and they retain their individual chemical and physical properties.
D. The atoms retain their individual chemical properties, and they can only be separated from each other by a chemical change.
Answer: A chemical compound can be described as substance composed of atoms from more than one element held together by chemical bonds in a fixed stoichiometric proportion. A compound has different physical and chemical properties from its constituent elements.
For example : compound water is made up of H and O bonded together and it has different properties from O and H.
Thus, among the given options, the one coreectly describing a compound is
a) The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
Question 6 of 25
When nonionizing radiation is absorbed by matter, it usually becomes which
type of energy?
A. Thermal
B. Mechanical
C. Electromagnetic
O D. Chemical
Answer:
thermal
Explanation:
a p e x
If 0.64 mol PCl5 is placed in a 1.0 L flask and allowed to reach equilibrium at a given temperature, what is the final concentration of Cl2 in the flask?
PCl5 (g)→ PCl3 (aq) + Cl2 (g) Kc= 0.47
Answer: The final concentration of [tex]Cl_2[/tex] at equilibrium is 0.36 M
Explanation:
Moles of [tex]PCl_5[/tex] = 0.64 mole
Volume of solution = 1.0 L
Initial concentration of [tex]PCl_5[/tex] = [tex]\frac{moles}{Volume}=\frac{0.64mol}{1.0L}=0.64 M[/tex]
The given balanced equilibrium reaction is,
[tex]PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)[/tex]
Initial conc. 0.64 M 0M 0M
At eqm. conc. (0.64-x) M (x) M (x) M
The expression for equilibrium constant for this reaction will be,
[tex]K_c=\frac{[Cl_2]\times [PCl_3]}{[PCl_5]}[/tex]
Now put all the given values in this expression, we get
[tex]0.47=\frac{(x)\times (x)}{(0.64-x)}[/tex]
By solving the term 'x', we get :
x = 0.36
Thus, the final concentration of [tex]Cl_2[/tex] at equilibrium is x = 0.36 M
The concentration of Cl2 is 0.36M.
Number of moles of PCl5 = 0.64 mol
Volume = 1.0 L
Concentration of PCl5 = 0.64 mol/1.0 L = 0.64 M
The equation of the reaction is;
PCl5 (g)→ PCl3 (aq) + Cl2 (g)
I 0.64 0 0
C -x +x +x
E 0.64 - x x x
Kc = [PCl3] [Cl2]/[PCl5]
0.47 = x^2/0.64 - x
0.47(0.64 - x) = x^2
0.3 - 0.47x =x^2
x^2 + 0.47x - 0.3 = 0
x = 0.36 M
The concentration of Cl2 is 0.36M.
Learn more about concentration:https://brainly.com/question/1195122
Write the word equation for
the reaction between sodium
hydrogen carbonate and
sulfuric acid.
Answer:
NaHCo3+Na2So4---Nna2So4+H2O+CO2
Answer:
sodium two sulphate+Carbondioxed gas +water
Ethane is a hydrocarbon with a formula of C2H6 . How many Carbon and Hydrogen atoms are contained within 3 molecules of ethane ?
Answer:
Within three molecules of Ethane, it would have 6 carbon, and 18 hydrogen atoms in it.
Explanation:
WILL MARK BRAINLIST
If a car travels 60 miles for two hours, what is the average speed?
15 mi/hr
30 mi/hr
45 mi/hr
60 mi/hr
Answer:
The average speed must be 30mph so this means the car traveled for 2hrs 60/30
Which word best describes the relationship between polyps and algae
exoskeletal
Bleached
Photosynthetic
Symbiotic
Answer:
symbiotic
Explanation:
There like a close friendship
A hydrogen atom is removed from the first carbon atom of a butane molecule and is replaced by a hydroxyl group.
Required:
Draw the new molecule formed.
Answer:
See answer below
Explanation:
In this case, let's draw the butane molecule:
CH₃ - CH₂ - CH₂ - CH₃
According to what the exercise states, we removed an atom of hydrogen from the frist carbon. This could be any of the terminals. I'll grab the first from left to right.
CH₂⁺ - CH₂ - CH₂ - CH₃
When this happens, the atom of carbon is lacking one space and it forms a carbocation.
Followed this step, an hydroxile group replace the atom of hydrogen. The hydroxile is the OH, and when we have an alkane with an OH group in the molecule, we are actually converting this molecule into an alcohol, therefore the molecule formed is:
OH - CH₂ - CH₂ - CH₂ - CH₃Hope this helps
An aqueous solution of nitric acid is standardized by titration with a 0.174 M solution of barium hydroxide. If 13.9 mL of base are required to neutralize 28.7 mL of the acid, what is the molarity of the nitric acid solution?
Answer:
Explanation:
2HNO₃ + Ba( OH)₂ = Ba( NO₃ )₂ + 2H₂O .
2 mole 1 mole
13.9 mL of .174M barium hydroxide contains .0139 x .174 moles
= 2.42 x 10⁻³ moles .
1 mole of barium hydroxide reacts with 2 moles of nitric acid
2.42 x 10⁻³ moles of barium hydroxide will react with 2 x 2.42 x 10⁻³ moles of nitric acid
= 4.84 x 10⁻³ moles
4.84 x 10⁻³ moles of nitric acid is contained in 28.7 mL
molarity of nitric acid = 4.84 x 10⁻³ / 28.7 x 10⁻³
= .169 M .
Write the line notation for a cell in which the cell reaction is as follow
H2 + I2 = 2 HI
Answer:
I2(g)/I^-(aq)//H2 (g)/H^+(aq)
Explanation:
Let us remember that in every redox reaction, a specie is oxidized and a specie is reduced.
This means that one specie looses electrons while the other species gains electrons.
Considering the overall reaction; H2 + I2 = 2 HI
Oxidation half equation;
H2 (g) ------> 2H^+(aq) + 2e
Reduction half equation;
I2(g) + 2e ------> 2I^-(aq)
Line notation;
I2(g)/I^-(aq)//H2 (g)/H^+(aq)
Prokaryotic cell division is a___________process involving onc chromosom.
A. simple
B. complex
C. unusual
Answer:
It’s is a simple
Explanation:the prokaryotic cell involves a simple process which intern involves one chromosom
The yield for a particular well is 280 gallons per minute (gpm). Of the drawdown for this well is 23 feet, what is the specific yield in gpm/ft?
Answer:
[tex]Y=12.2 \frac{gpm}{ft}[/tex]
Explanation:
Hello!
In this case, since we can find that the well produces 280 gpm, and the given drawdown is 23 ft, we need to divide 280 by 23 to obtain the yield in gmp/ft as shown below:
[tex]Y=\frac{280gpm}{23ft} \\\\Y=12.2 \frac{gpm}{ft}[/tex]
Best regards!
The following table lists molecular weight data for a polypropylene material. Molecular Weight Range (g/mol) xi wi
8,000 - 16,000 0.07 0.03 16,000 - 24,000 0.15 0.09 24,000 - 32,000 0.26 0.21 32,000 - 40,000 0.27 0.27 40,000 - 48,000 0.18 0.28 48,000 - 56,000 0.07 0.12
Click here to access Table 14.3. Atomic weights for several elements are included in the following table: Carbon 12.01 g/mol Chlorine 35.45 g/mol Fluorine 19.00 g/mol Hydrogen 1.008 g/mol Oxygen 16.00 g/mol Nitrogen 14.01 g/mol Compute the following:
(a) the number-average molecular weight, Enter your answer for part (a) in accordance to the question statement g/mol
(b) the weight-average molecular weight, Enter your answer for part (b) in accordance to the question statement g/mol
(c) the degree of polymerization.
Answer:
a) the number-average molecular weight is 32,400 g/mol
b) the weight-average molecular weight is 36,320 g/mol
c) the degree of polymerization is 770
Explanation:
Given the data in the question;
Molecular Mean Number Weight Number Weight
weight average average
(g/mol) Mi(g/mol) xi wi xiMi wiMi
8,000-16,000 12,000 0.07 0.03 840 360
16,000-24,000 20,000 0.15 0.09 3000 1800
24,000-32,000 28,000 0.26 0.21 7280 5880
32,000-40,000 36,000 0.27 0.27 9720 9720
40,000-48,000 44,000 0.18 0.28 7920 12320
48,000-56,000 52,000 0.07 0.12 3640 6240
∑ Mn=32,400 Mw=36,320
so;
a) the number-average molecular weight
Mn = ∑Mixi
so from the table above; summation of Row Mixi
Mn = ∑Mixi = 32,400
Therefore, the number-average molecular weight is 32,400 g/mol
b) the weight-average molecular weight
Mw = ∑Miwi
so from the table above; summation of Row Miwi
Mw = ∑Miwi = 36,320
Therefore, the weight-average molecular weight is 36,320 g/mol
c) the degree of polymerization
the degree of polymerization of polypropylene can be determined using number-average molecular and repeat unit molecular weight.
now, for polypropylene { CH₂ = CH - CH₃ }
the repeat unit consist of 3 carbon atoms and 6 hydrogen atoms
given that;
Atomic weight of Carbon mC = 12.01 g/mol and
Atomic weight of Hydrogen mH = 1.008 g/mol
now we find the repeat unit molecular weight of polypropylene
m = nCmC + nHmH
where n is the number of repeat of atoms
so we substitute
m = ( 3 × 12.01) + ( 6 × 1.008)
m = 36.03 + 6.048
m = 42.078 g/mol
now we calculate the degree of polymerization;
DP = Mn / m
so we substitute
DP = 32,400 / 42.078
DP = 769.9985 ≈ 770
Therefore, the degree of polymerization is 770
A car changes its velocity from 0 m/s to 14 m/s in 2 seconds.
What is the acceleration
Answer:
7
Explanation:
You divide the 14m/s by 2 and get the answer of the acceleration of 7
Describe how moving the mountain lions could affect the ecosystem
Answer:
If Mountain lions are removed from a habitat/ecosystem, their prey will overpopulate, which may lead to extinctions on the pray of the secondary consumers. ex. A mountain lion would eat rabbits who eat berries, if there are no mountain lions to kill the rabbits, then the berries may be scarce
Explanation:
bc i know everthing
